The efficiency of the Rankine cycle
A Rankine cycle can be regarded as a modified Carnot cycle.
In a Carnot cycle steam from a turbine is condensed only partially to liquid - and a feed pump or compressor must compress a mixture of liquid and vapor to boiler pressure. For handling both liquid and vapor a large compressor is required.
In a Rankine cycle steam from a turbine is condensed completely to liquid - and the liquid can be compressed to boiler pressure with a relatively small feed pump.
The efficiency of the Rankine cycle can be expressed as
μR = Hi - He / Hi - hc (1)
μR = Rankine efficiency
Hi = heat at turbine inlet (kJ/kg)
He = heat at turbine outlet (kJ/kg)
hc = sensible heat in exhaust (kJ/kg)